Torque-Compensating Wrist Brace With Six-Bar Linkage
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Solution Overview
Problem
Current assistive devices for stroke victims with wrist spasticity only provide assistance in one direction of wrist movement and do not effectively counteract the increased torque demand as the angular rotation increases, failing to mitigate intrinsic stiffness in both flexion and extension.
Innovation Solution
A torque-compensating assistive wrist brace with a spring-actuated six-bar linkage that provides angle-dependent supporting torque to balance and cancel out the increased torque imposed by wrist stiffness, allowing for easier movement and maintenance of desired angular positions in both flexion and extension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single-direction assistive device is used to provide torque to the wrist, then assistance is provided in one direction of movement, but the device fails to provide assistance in both flexion and extension directions
Solution Approach 1:
The six-bar linkage mechanism is designed to provide assistive torque in multiple directions (both flexion and extension) simultaneously, making the device universal for bidirectional wrist movement assistance rather than unidirectional support
2Ease of operation
If assistive torque is provided to the wrist, then movement assistance is improved, but the assistive torque decreases as angular rotation increases, which is opposite to what is needed
Solution Approach 1:
The six-bar linkage mechanism dynamically adjusts the assistive torque output based on the wrist's angular position, providing higher torque when rotation difficulty increases and maintaining appropriate force levels throughout the full range of motion
3Ease of operation
If wrist spasticity is present, then wrist stiffness and resistance to stretch increase, but the intrinsic stiffness cannot be effectively mitigated by conventional devices
Solution Approach 1:
The six-bar linkage mechanism generates counteracting torque that balances and neutralizes the excessive stiffness force produced by spastic wrist muscles, effectively canceling out the harmful intrinsic stiffness to enable smoother movement
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The wrist brace significantly reduces the effort required to achieve or hold desired angular wrist positions by counteracting intrinsic stiffness, enabling more effective wrist movement and maintaining a range of motion with reduced resistance.
Implementation Method 1
a spring-actuated six-bar linkage that provides angle-dependent supporting torque
Data Source
AI summary
In one embodiment, a torque-compensating assistive wrist brace includes a hand member adapted to be provided on a user's hand, a forearm member adapted to be provided on the user's forearm, and an assistive linkage that connects the hand and forearm members together, the assistive linkage being configured to apply a balancing torque to a wrist of the user that counteracts intrinsic stiffness within the wrist and assists the user in rotating the wrist in both the flexion and extension directions.